Pregnancy outcome has been studied in terms of legal abortions, early spontaneous abortions and total number of pregnancies (in an ad hoc study covering 6 counties) as well as various perinatal health problems (on the basis of routinely recorded data for epidemiological surveillance from the Medical Birth Registry of Norway). Apparently, no effects were observed in terms of an increased occurrence of legal abortions, while spontaneous abortions increased from 7.2% of all pregnancies during the last 12 months before the accident to 8.3% after the accident [corrected]. At the same time, the total number of pregnancies somewhat decreased. Based on monthly measurements in each municipality of external and internal (food-based) doses, dose-response associations were assessed for a number of perinatal health problems. No associations were observed.
PIP: The effects of Chernobyl on pregnancy outcome were investigated in Norway in terms of legal abortions, early spontaneous abortions, total pregnancies, and perinatal health problems (cataracts, microcephaly, low birth weight, and perinatal mortality). The epidemiological results showed that there were no serious gross changes in pregnancy outcome in Norway after Chernobyl in 1986. Anxiety may have led to the temporary decrease in pregnancies. The statistically significant difference in spontaneous abortions between 19867 and 1987, particularly in the months following Chernobyl, may be related but causation cannot be determined based on the present data; i.e., dietary changes due to anxiety may also be related. Further analyses will be conducted with data spanning 5 years after Chernobyl. The Central Bureau of Statistics provided data on legal abortions as reported by hospitals to county medical officers. Spontaneous abortions (16 weeks) are based on ad hoc notifications from hospitals in 5 counties: Aust-Agder, Hordaland, Oppland, Troms, and Trondelag. Compulsory notification of births is recorded in the Medial birth Registry and includes congenital malformations and other perinatal health problems. The National Institute of Radiation Hygiene recorded data after the accident on indoor gamma rates, radiocesium (Cs 134) soil samples, and municipality specific average food-based dose equivalents of Cs 134 and 137 in meat and meat supplies. The total external and internal dose is provided for May 1986-April 1989. Food-based doses remained at an elevated level for an extended period of time. Infant exposure was considered form the 2nd month of gestation. Legal abortions, induced or spontaneous, were not impacted by Chernobyl, but the effect may have been delayed to the 3rd or 4th quarter with a 1.0% increase. However, at Haukeland Hospital in Bergen, the highest abortion rates were 19.1% in 1985-86 and 19.2% in 1986-87. Pregnancies temporarily decreased in the 3rd and 4th quarters following the accident in a period usually reflecting annual increases. Cataract occurrences increased the year after the accident with 8 observed and 3.8 expected, but the P value was insignificant (P=.74). Microcephaly followed a similar pattern. Birth 2500 gms had observed values of 2726 vs. 2639.2 expected, an insignificant P value of .99. Observed perinatal deaths of 634 were less than the 718.8 expected.